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Radon Levels in Armstrong County, Pennsylvania

EPA puts Armstrong County in Zone 1, its highest radon zone, and high results are common there: 47.6% of the 187 radon tests reported to CDC (2020) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    47.6%

    17.3 pts above PA

    Armstrong
    47.6%
    PA
    30.3%

    187 tests, 2020

  • Median result

    3.7pCi/L

    Below action level

    Armstrong
    3.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2020

  • Tests reported

    187

    45th of 63 by tests

    Armstrong
    187
    Montgomery
    10,508

    Reported to CDC before any fix, 2020

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in PA

    9 of 63

    Top quarter

    Armstrong
    47.6%
    Perry
    57.7%

    By share, of 63 with 30+ tests

Read a result for Armstrong County

Starts at Armstrong County's median, 3.7 pCi/L

3.7pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 3.7 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Armstrong County's median reported result, 2020.

Interpret this readingWhat a fix costs

The data

Armstrong County, At a glance

Armstrong County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Armstrong County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Armstrong County, 2020

Share of reported tests at or above 4 pCi/L, by year, Armstrong County
Share of reported tests at or above 4 pCi/L, by year, Armstrong County
YearShare of reported tests at or above 4 pCi/L
201455.6%
201556.0%
201654.2%
201752.4%
201852.9%
201946.9%
202047.6%

2020: 47.6%. Across these years the share ran from 46.9% to 56.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 187 tests reported to CDC for Armstrong County over 2020, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

How to read these figures

Armstrong County, Compared

Armstrong County radon figures, compared

Calculated by Radon411

In Armstrong County, about 5 in 10 reported tests in 2020 (89 of 187) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 22.1 points higher. Across 67 Pennsylvania counties pooled together, 30.3% of tests reached that level, so Armstrong County runs 17.3 points above its state.

Of 6 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 30.5% (Allegheny County) to 44.3% (Indiana County). By share, Armstrong County is 9th of 63 Pennsylvania counties with 30 or more tests for the same period.

Year by year, 2014 opened at 55.6% and 2020 closed at 47.6% (down 8.0 points), with 2015 the high at 56.0%. Half the tests came in under 3.7 pCi/L and half over it; the single highest reached 200.1 pCi/L. Below the action level, 51 tests (27.3%) came in under 2 pCi/L, against 44.3% statewide, and 47 tests (25.1%) fell between 2 and 4, against 25.4% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 47.6% share point the same way here. USGS geology rates 100% of the county's land high radon potential.

The busiest year on file was 2015, with 218 tests reported; the quietest, 2017, had 143.

Share of reported tests at or above 4 pCi/L by year, Armstrong County against Pennsylvania2014 to 2020, years with 30 or more tests: Armstrong County 55.6% to 47.6%, the state's pooled share 30.3% in 2020.
Armstrong CountyPennsylvania, pooled
Share of reported tests at or above 4 pCi/L by year, Armstrong County against Pennsylvania: data table
YearTestsArmstrong County, at or above 4 pCi/LPennsylvania, pooled
201419855.6%36.1%
201521856.0%37.8%
201620154.2%34.4%
201714352.4%35.1%
201817252.9%30.5%
201920946.9%31.4%
202018747.6%30.3%
Armstrong County against Pennsylvania, the United States and nearby counties, 2020
AreaTestsAt or above 4 pCi/LMedianDifference from Armstrong County
Armstrong County18747.6%3.7 pCi/LThis county
Pennsylvania, pooled67 counties, pooled93,66930.3%Not pooled−17.3 points
United States, pooled915 counties, pooled405,35525.5%Not pooled−22.1 points
Perry Countyhighest in the state18957.7%4.9 pCi/L+10.1 points
Philadelphia Countylowest in the state8,44210.6%1.7 pCi/L−37.0 points
Indiana County, PAborders it22844.3%3.6 pCi/L−3.3 points
Butler County, PAborders it1,49242.3%3.3 pCi/L−5.3 points
Jefferson County, PAborders it25438.6%2.6 pCi/L−9.0 points
Westmoreland County, PAborders it1,58834.9%2.6 pCi/L−12.7 points
Clarion County, PAborders it10731.8%2.9 pCi/L−15.8 points
Allegheny County, PAborders it8,33730.5%2.5 pCi/L−17.1 points
Where Armstrong County's reported results fell, 2020, beside Pennsylvania and the United States
ResultArmstrong County testsArmstrong County sharePennsylvania shareU.S. shareAgainst Pennsylvania
Under 2 pCi/L5127.3%44.3%51.6%−17.0 points
2 to 4 pCi/L4725.1%25.4%22.9%−0.3 points
4 pCi/L and above8947.6%30.3%25.5%+17.3 points
Armstrong County ranked among the 63 Pennsylvania counties with 30 or more tests, by share at or above 4 pCi/L, 2020
CountyRankTestsAt or above 4 pCi/LMedian
Huntingdon County4 of 6310054.0%4.5 pCi/L
Schuylkill County5 of 6379753.5%4.5 pCi/L
Juniata County6 of 638752.9%4.4 pCi/L
Northumberland County7 of 6327549.8%3.9 pCi/L
Bedford County8 of 636947.8%3.8 pCi/L
Armstrong County9 of 6318747.6%3.7 pCi/L
Clearfield County10 of 6339447.5%3.6 pCi/L
Elk County11 of 636647.0%3.5 pCi/L
York County12 of 633,67946.8%3.6 pCi/L
Lycoming County13 of 6356245.2%3.5 pCi/L
Tioga County14 of 6316045.0%3.2 pCi/L
Armstrong County radon tests by year, against Pennsylvania's pooled share
YearTestsAt or above 4 pCi/LMedianHighestPennsylvania, pooledChange from the row before
202018747.6%3.7 pCi/L200.1 pCi/L30.3%+0.7 points
201920946.9%3.5 pCi/L75.8 pCi/L31.4%−6.0 points
201817252.9%4.5 pCi/L254.2 pCi/L30.5%+0.5 points
201714352.4%4.1 pCi/L198.6 pCi/L35.1%−1.8 points
201620154.2%4.7 pCi/L58.6 pCi/L34.4%−1.8 points
201521856.0%4.5 pCi/L118.2 pCi/L37.8%+0.4 points
201419855.6%4.4 pCi/L343.0 pCi/L36.1%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Armstrong County, State data

Pennsylvania's own radon test data

Measured

What Pennsylvania's own agencies publish about radon tests in Armstrong County, with their period. These are not CDC's figures and are never added to them.

MeasuredState figures, not CDC's

What Pennsylvania DEP reports for the ZIP codes in Armstrong County

Pennsylvania DEP publishes its figures by ZIP code, not by county. These are the 36 ZIP codes that lie wholly or partly in Armstrong County, each with the state's own figures for it. Period: Period not stated by DEP.

ZIP codes in Armstrong County
ZIP codeWhat the state reports
15613Basement: average 10.2 pCi/L, 1,442 tests; First floor: average 6.1 pCi/L, 99 tests
15618Basement: average 4.7 pCi/L, 99 tests; First floor: figures not shown
15656Basement: average 6.1 pCi/L, 847 tests; First floor: average 9.2 pCi/L, 60 tests
15673Basement: average 5.1 pCi/L, 48 tests
15682Basement: figures not shown
15686Basement: average 23.4 pCi/L, 105 tests; First floor: figures not shown
15690Basement: average 5.0 pCi/L, 410 tests; First floor: figures not shown
15732Basement: average 6.2 pCi/L, 107 tests; First floor: figures not shown
15736Basement: figures not shown; First floor: figures not shown
15774Basement: average 10.7 pCi/L, 163 tests; First floor: figures not shown
16025Basement: average 14.5 pCi/L, 309 tests; First floor: average 8.3 pCi/L, 31 tests
16028Basement: average 13.7 pCi/L, 50 tests
16041Basement: average 25.9 pCi/L, 93 tests; First floor: figures not shown
16049Basement: average 14.4 pCi/L, 79 tests; First floor: figures not shown
16055Basement: average 9.8 pCi/L, 1,378 tests; First floor: average 5.0 pCi/L, 72 tests
16201Basement: average 10.8 pCi/L, 882 tests; First floor: average 5.3 pCi/L, 70 tests
16210Basement: figures not shown; First floor: figures not shown
16212Basement: figures not shown; First floor: figures not shown
16218Basement: average 11.5 pCi/L, 50 tests; First floor: figures not shown
16222Basement: average 11.9 pCi/L, 47 tests; First floor: figures not shown
16224Basement: average 10.1 pCi/L, 51 tests; First floor: figures not shown
16226Basement: average 7.1 pCi/L, 305 tests; First floor: average 5.3 pCi/L, 37 tests
16228Basement: figures not shown; First floor: figures not shown
16229Basement: average 10.9 pCi/L, 458 tests; First floor: average 10.5 pCi/L, 36 tests
16236Basement: figures not shown; First floor: figures not shown
16238Basement: figures not shown; First floor: figures not shown
16240Basement: figures not shown; First floor: figures not shown
16242Basement: average 9.8 pCi/L, 179 tests; First floor: figures not shown
16244Basement: figures not shown
16245Basement: figures not shown
16249Basement: average 12.4 pCi/L, 66 tests; First floor: figures not shown
16250Basement: figures not shown; First floor: figures not shown
16253Basement: figures not shown; First floor: figures not shown
16259Basement: figures not shown; First floor: figures not shown
16262Basement: average 9.8 pCi/L, 100 tests; First floor: figures not shown
16263Basement: figures not shown
  • DEP's report gives the number of tests, the highest result and the average result for each floor tested; it states no period.
  • DEP says the smartest thing to do is to test your home for radon, no matter where you live.
  • A ZIP code that crosses the county line is listed whole; its figures cover all of it.

Measured: Pennsylvania DEP data, Period not stated by DEP.

Armstrong County, Geology

The ground under Armstrong County

Predicted

USGS's geologic map puts all of Armstrong County's mapped land in one class: high radon potential. All of it lies in the area the map calls Pennsylvanian Rocks of the Pittsburgh Low Plateau, to which USGS gives a radon index of 14, in the high band (12 to 17).

USGS's geologic areas under Armstrong County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Pennsylvanian Rocks of the Pittsburgh Low PlateauPennsylvanian marine shale, siltstone, sandstone, limestone, and coal.High14100%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Armstrong County beside the ground around it

Armstrong County has more high-potential ground than Pennsylvania as a whole: 100% of its land against 70.4%. Of the 6 counties that border it, none has as large a share of high-potential ground; Allegheny County comes nearest at 100%.

Share of land by USGS radon potential: Armstrong County, the 6 counties bordering it and Pennsylvania
AreaEPA zoneLow potentialModerate potentialHigh potential
Armstrong CountyZone 1NoneNone100%
Indiana CountyZone 1None23.2%76.8%
Clarion CountyZone 1None2.0%98.0%
Butler CountyZone 1None2.0%98.0%
Jefferson CountyZone 2None63.7%36.3%
Westmoreland CountyZone 1None34.6%65.4%
Allegheny CountyZone 1NoneNone100%
Pennsylvania67 counties, pooled by land areaVaries0.7%28.9%70.4%

The map rates the ground, not the air in any home.

Local help

Armstrong County, Local resources

Radon testing and mitigation in Armstrong County

What Pennsylvania's program says
Phone
800-237-2366
Licensing of radon professionals
The Radon Certification Act requires DEP to establish by regulation, a certification program for persons conducting radon gas and radon progeny testing, laboratory analysis and mitigation of radon contamination in buildings.

What it means

Armstrong County, Questions

Questions about radon in Armstrong County

Are radon levels high in Armstrong County?

In 2020, 47.6% of the radon tests reported to CDC for Armstrong County, Pennsylvania were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.7 pCi/L. Of 63 Pennsylvania counties with 30 or more tests for the same period, 8 reported a higher share; pooled, the state comes to 30.3%.

Which counties border Armstrong County?

Armstrong County borders 6 counties: Indiana County, Clarion County, Butler County, Jefferson County, Westmoreland County and Allegheny County.

Products

Armstrong County, Products

Testing a home in Armstrong County

In Armstrong County, 47.6% of 187 tests reported to CDC in 2020 reached 4 pCi/L, against 30.3% pooled across Pennsylvania. In Zone 1 the year-round level in Armstrong County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Armstrong County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Armstrong County

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Armstrong County, Bordering counties

Counties bordering Armstrong County

Calculated by Radon411

Armstrong County, Cities and towns

Cities and towns in Armstrong County

About 63,698 people live in Armstrong County by the Census Bureau's estimate for July 1, 2025, 1,798 fewer than in 2020 (−2.7%). That works out to 97 people per square mile of land. No town dominates: Kittanning, the largest, has 3,941 residents, 6.2% of the total. Together its 17 incorporated places hold 29.5% of those residents; the other 70.5% live outside any of them. Reported testing is thin here: 187 tests over 2020, or 2.9 for every 1,000 residents (2025 estimate), where Pennsylvania as a whole comes to 7.2.

From Kittanning to Atwood, CDC publishes no figure by town: each reads Armstrong County's.

The 12 largest cities and towns in Armstrong County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Kittanning3,941+0.5%6.2%
Ford City2,750−3.8%4.3%
Leechburg2,068−3.7%3.2%
Freeport1,672−3.8%2.6%
Apollo1,537−3.8%2.4%
North Apollo1,212−3.6%1.9%
West Kittanning1,152−3.8%1.8%
Rural Valley798−3.6%1.3%
Parker674−3.4%1.1%
Worthington566−3.7%0.9%
Dayton528−3.6%0.8%
South Bethlehem464−3.7%0.7%
  • Manorville
  • Ford Cliff
  • Applewold
  • Elderton
  • Atwood

17 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

Armstrong County, Homes

Homes in Armstrong County

Armstrong County is a place of houses on their own lots: 78% of its 32,164 homes are detached single-family houses, against 57% across Pennsylvania. Half of its homes were built before 1960, close to Pennsylvania's 1965: 51% date from before 1960 and 9% from 2000 or later. Owners live in 79% of the occupied homes (Pennsylvania: 69%), so for most households a test and a fix are their own to order.

Homes in Armstrong County, Pennsylvania, 2019 to 2023
HomesArmstrong CountyPennsylvania
Housing units32,1645,779,663
Detached houses78%57%
In buildings of 5 or more5%13%
Mobile homes9%4%
Built before 196051%45%
Built since 20009%14%
Middle year built19601965
Owner-occupied79%69%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.